Forge furnace

ABSTRACT

This forge furnace has a rotary barrel with means to periodically rotate the barrel and thereby cause the stock therein to roll around. A vibratory feed mechanism is provided at the material inlet end to move the stock longitudinally when the barrel is not rotating. Molded refractory inserts are placed in the barrel to provide passageways for the stock and the heating gases. A stationary compartment with burners that produce a reducing gas mixture is provided at the stock outlet end.

United States Patent [191 Eliot FORGE FURNACE [75] inventor: Sigdon A.Eliot, Worthington, Ohio [73] Assignee: Consolidated Natural Gas ServiceCompany, Inc., Pittsburgh, Pa.

[22] Filed: June 15, 1972 [21] Appl. No.: 263,251

Related US. Application Data [63] Continuation-in-part 'of Ser. No.83,097, Oct. 22,

1970, abandoned.

[52] US. Cl 432/34, 432/45, 432/105, 432/106, 432/118 [51] Int. Cl. F27b7/14 [58] Field of Search 432/103, 105, 108, 111, 432/118, 119, 34, 45

[56] References Cited UNITED STATES PATENTS 1,372,406 3/1921 Derneden432/118 2,230,142 1/1941 Longacre 432/118 2,371,335 3/1945 Kritscher432/34 June 11, 1974 3,326,542 6/1967 Mescher et a1. .1 432/34 FOREIGNPATENTS OR APPLlCATlONS 1,210,060 6/1901 Germany 432/103 PrimaryExaminer-John J. Camby Atmrney, Agent, or Firm-Jerome R. Cox

[ ABSTRACT This forge furnace has a rotary barrel with means toperiodically rotate the barrel and thereby cause the stock therein toroll around.

A vibratory feed mechanism is provided at the material inlet end to movethe stock longitudinally when the barrel is not rotating.

Molded refractory inserts are placed in the barrel to providepassageways for the stock and the heating gases.

A stationary compartment with burners that produce a reducing gasmixture is provided at the stock outlet end.

57 Claims, 18 Drawing Figures PATENTEDJUNI 1 mm 3131 61364 SHEET 2 OF 7PATENTEDJIIM 1 W4 38 161364 sum 50$ 1 PA'TENYEDM 1 1 I914 33 16064 sawear 7 FORGE FURNACE CROSS-REFERENCE TO RELATED APPLICATIONS Thisapplication is a continuation-in-part of the application of Sigdon A.Eliot, the inventor herein, Ser. No. 083,097 filed Oct. 22, 1970 andallowed Mar. 17, 1972, now abandoned.

- BACKGROUND The invention relates to the continuous heating ofobjects,and more particularly relates to the heating of forging stockprior to its being forged.

The forging of stock into articles requires that the stock be initiallyheated to a temperature, such as 2,l F., before it is inserted into theforge and hammered to shape. The correct practice is to lay the bars ofstock parallel and side by side on the horizontal flat hearth of an openfront slot type furnace. Such a furnace has gas or oil burners atopposite ends which apply heat transversely to the bars. The furnace islocated near the forge. Stock is laid on the hearth and heated until itreaches the desired temperature. Then the bars of stock are removed byan operator one by one and forged.

This system of heating the stock prior to forging has severaldisadvantages which the invention overcomes. The fuel is inefficientlyused. The burning gases, ignited at the burner, pass immediately overthe bars and are exhausted into the atmosphere. They are exhausted at atemperature very close to their maximum temperature so that asubstantial quantity of the heat capacity of the fuel is lost.

Stock heated by laying on a hearth is not uniformly heated. The portionsof each bar which contact the hearth will not be as hot as thoseportions exposed directly to the burner flame. When such bars arepositioned side by side, each bar is in the shadow of one or more of theothers. This, of course, blocks radiation to portions of the bars.

The open front of the conventional furnace permits the entry ofoxygen-containing air. As hot gases escape upwardly by convection, airenters the lower part of the opening and contributes to theoxidation-scaling of the bars and a consequent deterioration of quality.

Therefore, it is an object of the invention to provide an improved forgefurnace.

A further object is to provide a forge furnace which more efficientlyutilizes its fuel.

A further object is to provide a forge furnace which uniformly heatsbars of forging stock.

Another object is to provide a forge furnace which nearly eliminates thescaling of forging stock.

Yet another object is to provide for automatic control of both the barstock delivery rate and the bar stock temperature.

Further objects and features of my invention will be apparent from thefollowing specification and claims when considered in connection withthe accompanying drawings illustrating several embodiments of myinventron.

SUMMARY OF THE INVENTION 1 have found that the foregoing and otherobjects may be attained in a furnace having a substantially horizontal,rotatably mounted barrel in the nature of a tumbler barrel, although theforging stock or billets roll rather than tumble; a drive means for attimes rotating the barrel and thereby rolling bars of forging stockaround the interior of the barrel or around the interior of each of theconcentric tubular passageways without substantial longitudinal movementof the stock: means for at times moving the stock longitudinally alongthe barrel; heating means for supplying heat into the end of the barrelout of which the heated stock is delivered either from one burner or twoor more burners; means for supplying heat in the form of a reducing gasmixture at the forging stock outlet end of the furnace where thetemperature is highest so that said reducing gas surrounds the stock andmoves toward the object inlet end; means for mixing an oxidizing gasmixture or pure air with the reducing gas mixture at a portion of thefurnace farther from the outlet end thereof where the forging stocktemperature is lower and thus is not as susceptible to scale formationso that complete combustion is achieved while at the same time scale issubstantially eliminated; and means for increasing the capacity of sucha furnace withoutexcessive length by providing a plurality oflongitudinally extending passageways concentrically around the core ofthe furnace.

Further objects are obtained by utilizing a preheat oven, positioned toreceive heat from the end of the barrel, in which the bars of stock canbe stacked and from which they can be injected into the tumbler barrel.

Still further objects are obtained in a refractory furnace core or linerfor use in an outer furnace shell, the liner comprising a hollowrefractory core having an inner wall portion defining the inner wall ofthe furnace and an outer wall portion which is supported by and spacedfrom the shell and held at a uniform distance therefrom.

DESCRIPTION OF THEVIEWS FIG. 1 is a plan view of one embodiment of theinvention;

1 FIG. 2jis a view in side elevation of the embodiment of FIG. 1;

FIG. 3 is a view in vertical section taken substantially along the line33 of FIG. 2;

FIG. 4 is a view in side elevation of the furnace shown in FIG. 2 beingfragmentary and showing the outlet end of the barrel, the burner and thetrap door, being taken from the opposite side of the side elevation ofFIG. 2 and having parts broken away and shown in section;

FIG. 5 is a view in side elevation of a fragment of the furnace shown inFIG. 2 looking at the furnace from the opposite side of the sideelevation of FIG. 2 and having parts broken away and shown in section;

FIG. 6 is a view in vertical section taken along the line of 6-6 in FIG.5, further illustrating the structure;

FIG. 7 is a view in end elevation of a refractory insert constructedaccording to the invention and used in the embodiment shown in FIGS. 1,2, 3, 4, 5, and 6;

FIG. 8 is a view in side elevation of the insert illustrated in FIG. 7;

FIG. 9 is a schematic view of the control circuit used to control theoperation of the embodiment illustrated in FIGS. 1-8;

FIG. 10 is a view in plan similar to FIG. 1 but showin a differentembodiment of my invention;

FIG. 11 is a view in end elevation of the embodiment of FIG. takensubstantially on the line ll-ll of FIG. 10;

FIG. 12 is a view in side elevation of the furnace shown in FIG. 10;

FIG. 13 is a fragmentary view in perspective of a portion of theembodiment of the furnace shown in FIG. 10 being on an enlarged scaleand having sections broken away so as to shown the core of the furnaceand other interior elements;

FIG. 14 is a view in perspective showing one, of the core ceramicinserts of the embodiment of the invention shown in FIG. 10;

FIG. 15 is a fragmentary view in perspective with parts broken away tofurther illustrate the construction of the casing of the furnace shownin FIG. 10;

FIG. 16 is a fragmentary view in vertical section and on an enlargedscale taken substantially on the line 16-16 of FIG. 11;

FIG. 17 is a fragmentary view in enlarged vertical section takensubstantially on the line l7l7 of FIG. 10; and

FIG. 18 is a view in vertical section taken substantially on the line18l8 of FIG. 17.

In describing the embodiments of the invention illustrated in thedrawings, specific terminology will be resorted to for the sake ofclarity. However, it is not intended to be limited to the specific termsso selected, and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner toaccomplish a similar purpose.

DETAILED DESCRIPTION FIGS. 1 and 2 illustrate one assembled embodimentof the invention. A substantially horizontal rotatably mounted barrel 10is supported on a plurality of pairs of rollers such as 12a, 12b, 12c,12d, 12e, 12f, 12g, and 12h. These rollers are rotatably mounted insupport arms 14 which are welded to an underframe 16. Three top rollersl8a-18c are mounted on substantially horizontal beams 20a-20c which areheld above the barrel 10 by vertical struts such as vertical strut 22(FIG. 2). Thus the rollers 12a-l2h, together with the rollers l8a 18c,prevent radial movement of the barrel 10 and keep it cradled above theunderframe 16.

A pair of annular flanges 24 and 26 are welded to the exterior of thebarrel l0 and seat against a pair of horizontally rotatable wheels 28and 30 (FIG. 2) located beneath-the barrel 10 to prevent longitudinalmovement of the barrel. The barrel 10 is rotatably driven by a motor 32which is connected by suitable sprocket wheels and a drive chain 34 tothe barrel 1!).

The underframe l6 rests on a plurality of transverse horizontal channelmembers 36a-36f which in turn are supported on a vibration platform 38.The platform 38 has legs 40a-40c which are mounted on a base 42. Avibratory conveyor drive 44 using eccentric weights is mechanicallylinked by an arm 45 to the vibration platform 38 and is belt driven by amotor 46. The vibratory drive at times longitudinally vibrates thebarrel 10 to move objects longitudinally through the barrel.

At the outlet end 48 of the barrel 10 is a stationary cylindricalcompartment 49 to which a gas burner heating means 50 is mounted. Fuelis supplied to the burner 50 through a supply pipe 52. The compartment49 is mounted on a standard 54 (FIG. 2) and is provided with a trap door56 which is periodically opened to permit objects heated in the barrel10 to drop out. This structure is shown in more detail in FIG. 4 and isdescribed in more detail below.

The bar stock absorbs approximately 80 percent of its heat energy fromradiation. Relatively little heat comes from conduction from the gases.Consequently, and especially because the heat transfer by radiationvaries as the cube of the temperature (i.e. T it is desirable to heatthe inner walls of the barrel 10. Therefore, a burner may advantageouslycomprise two parts: one which directs a slightly oxidizing flame(maximum heat) at a slight angle against the top inner surface of thebarrel; the other would direct a reading flame (to reduce scaling)directly along the barrel. This provides a dual heat layer of gaseswhich will join further down the tube to, in effect, extend the flamefront along'the barrel. A preheat oven 70 is positioned to abut theinlet end 72 of the barrel l0 and is inclined to rise therefrom. Objectssuch as forging bar stock may be stacked in the preheat oven 70 and bepreheated by the hot gases passing from the barrel 10 through thepreheat oven 70.

The bottom of the preheat oven 70 is an inclined platform 74 (see alsoFIG. 5) which extends approximately radially upwardly and outwardly fromthe central axis of the barrel l0 and is covered on its top-and sides bya cover means 76 to form an enclosed inclined passageway. Objects suchas forge bar stock 112 can be stacked as shown in FIG. 1 and FIG. 5.Injection means, such as pneumatic cylinders 80 and 82 (FIG. 2), aremounted at the lower end of the oven 70 near the abut ting barrel 10 forselectively injecting the stacked objects from the preheat oven 70 intothe barrel l0as described in more detail below and illustrated in moredetail in FIG. 5.

FIG. 4 shows in greater detail the stationary compartment 49 which abutsand opens into the barrel 10. The

lined with a suitable refractory such as 90, A and 90B. The refractoryof the barrel 10 should have a substantially cylindrical inner surfaceso that during rotation of the barrel 10, the bar stock, designated 92in FIG. 4, will roll smoothly around the interior surface. It will notactually tumble, although the barrel 10 may be at times referred to as atumbler barrel. In this specification and in the claims, the wordstumbler barrel. are to be construed to mean a rotatable cylinder inwhich material moves around the cylinder while the cylinder rotateswhether it tumbles or not.

A trap door 56 is mounted by a hinge 94 to the underside of thestationary compartment 49. It has a counterweight 51 holding it closed.The door 56 may be opened, by a suitable device, such as a solenoid or afoot pedal, but I prefer a pneumatic cylinder 53 the plunger of which isconnected by a hinge pin 55 to an arm 57 extending from the trap door56.

An infra-red radiation-sensing temperature recorder 61 and its sightingtube 63 are mounted to the stationary compartment 49.

When the vibratory conveyor drive 44 (FIG. 2) is activated, the barstock 92 moves toward and into the stationary compartment 49 until itfalls, by gravity, onto the trap door 56. The weight of the bar stock 92will move the door to the position 56A where it will be held by thepneumatic cylinder 53 for a short period of time. While resting on thetrap door and laying in the center of the cylindrical wall, the bar ofstock will have its temperature measured and recorded by the temperaturerecorder 61 with its sighting tube 63. Then the pneumatic cylinder 53will be activated to move the trap door to the position 568 permittingthe bar stock to fall onto a table (not shown). An operator will lift itfrom the table and position it in the forge.

The temperature read by the temperature recorder 61 will also provide atemperature controlling signal. It is used with a conventional feedbackcontrol system which will control primarily gas value and secondaril thecycle period.

A viewing window 100 is mounted at one end of the stationary compartment49 to permit viewing of the contents of the barrel and the burner flame.The viewing window 100 is mounted in a tube 102 which is hingedlymounted to the stationary compartment 49 so that it can be opened forigniting the flame.

FIG. 4 and FIG. 5 respectively supplement FIGS. 1 and 2 to illustratethe compartment 49 as described above and the preheat oven 70 and theinjection means for selectively injecting bar stock or other objectsfrom the preheater into the tumbler barrel. The inclined platform 74 andits enclosing cover 76 extend upwardly and radially away from the barrel10 at an angle of about 45 to form the preheat oven 70. For large stock,the angle should be decreased for example, to about 25. The oven 70 islined with a suitable refractory 104 to form an enclosed passagewaythrough which hot gases from the tumbler barrel pass. The hot gasesenter the preheat oven through an opening 106 in the oven 70 which isopposite the inlet end 72 of the barrel. A ceramic stop 110 on thebottom of the preheat oven 70 retains stacked bar stock 112 which can bestacked along the inclined surface to the upper end (FIG. 1) of thepreheat oven 70.

As seen best in FIG. 6, a pneumatic cylinder 80 is mounted beneath thepreheat oven 70 near the stop 110. Its plunger 81 extends to a positionimmediately above the stop l10 so that when the pneumatic cylinder 80 isactuated, its plunger 81 pushes one bar stock (designated as 112 in FIG.6) above the stop 110. The bar 112 then falls to the position 112A (FIG.5 and 6) against a second stop 114.

Returning to FIG. 5, the bar stock at position 112A is now positioned tobe injected into the tumbler barrel 10 by the plunger 83 of thepneumatic cylinder 82. This injector plunger 83 is mounted approximatelyparallel to the longitudinal axis of the barrel so that, when actuated,it will strike the end of the bar stock at 112A and inject it into theinlet end 72 of the tumbler barrel 10. At the bottom end of preheat oven70, [have provided a door 116, visible in FIG. 6, which is mounted by ahinge 118 to the preheat oven l0. This door provides access to theinside of the preheat oven 70 for inspection or repair. In operation,the door 116 is kept closed and latched.

In FIG. 5, the section of the preheat oven is shown to be rectangular.However, it will be desirable in some circumstances to provide atrapezoidal cross section in order to provide heat transfer withimproved uniformity. For example, the side wall 301 might be shortenedso that the top 303 would be inclined downwardly from left to right inFIG. 5. This would cause the gases, which flow from the barrel l0 andturn up the preheat oven 70, to more uniformly transfer their heat tothe walls of the preheat oven 70.

It may also be desirable at times to provide an addtional separateheater for heating the preheat oven. Such an additional heater would beuseful in initially warming up the preheat oven and also would makeincreased delivery rates possible.

As another alternative. the preheater might have a plurality of smallparallel passages through which bar stock is pushed, as by a plunger tofeed the tumbler barrel 10.

Still another alternative is a longitudinal preheater with several (suchas seven. for example) longitudinal. parallel, tubular passagesextending through it. each one containing bars being heated. Such apreheater is substantially coextensive, with and is positioned parallelto the barrel 10 and next to it. Thereby much space is saved by thecompactness of the unit. If desired, the longitudinal preheater maypreferably be cylindrical. Also if desired, a suction fan may be used tosuck the heated gases through the preheater.

Means are provided for rotating the longitudinal preheater similar tothe means shown for rotating the barrel. However, though the barrel andthe preheater may rotate at identical speeds, the preheater may berotated faster or slower. In the machine which I have built, thepreheater rotates continuously. It is not necessary to have thepreheater pause for the vibration period of the barrel. Means areprovided for causing the objects to be heated to move from the inlet endof the preheater to the outlet end thereof.

A properly designed transfer box is provided to transfer the preheatedbars from the longitudinal preheater to the barrel.

Such a transfer box should be intermediate the preheater 74 and therotating barrel 10.

The design of the transfer box is very like the design of the preheatoven as shown in FIGS. 1, 2 and 6. It is much shorter than the preheater70 and only constitutes means for moving the objects from the outlet endof the preheat oven into the inlet end of the barrel. In my constructionthis last mentioned means includes a pneumatically operated plunger verylike the plunger associated with pneumatic cylinder 82 shown in FIGS. 1,2, and 5. This plunger is arranged and controlled to be automaticallyoperated as each of the longitudinal parallel tubular passages of thepreheater becomes aligned with the plunger. The transfer box does nothave a stop similar to stop 110 nor a pneumatically operated cylinderand plunger similar to and 81.

The forging stock (such as bars, for example) are fed cold into thepreheater. Such feeding may be done manually. However, I prefer thatthis be done automatically and in the furnace which I have built I haveprovided automatic means for feeding forging stock bars into thepreheater.

Adjacent the inlet side of the preheater, I provide a sloping platformor shelf. On the opposite side of the platform from the preheater, Iprovide a pneumatic cylinder similar to cylinder 82 and having apneumatically operated'plunger. Bars are fed automatically by gravity tothis platform one at a time so that when any longitu dinal passageway ofthe preheater becomes aligned with the plunger, the bar on the platformis also aligned between the plunger and the passageway of the preheater.Actuation of the plunger when the passageway of the preheater becomesaligned pushes the bar off of the platform and into the passageway ofthe preheater and thus pushes all other bars in that passageway for wardtherein. Thus a bar will be deposited at such time into the transfer boxand so fed into the furnace barrel when desired. Controls are providedso that this action takes place only when a bar is released from thebarrel furnace. It is to be understood that the circumference of eachpassageway is not equal to nor an exact multiple of the circumference ofthe bar so that as the preheater rotates, the bars (at the time ofalignment with the plunger) do not rest on the same side as before andare thus not subject to excessive abrasion.

The advantages of rotation of the preheater are several. For example (1)inasmuch as heat rises, were there not rotation, the forging stockobject at the top would be heated more intensively than forging stockobjects at other positions; (2) inasmuch as the forging stock objectswould without rotation always lay on the same side, pushing the stockthrough the preheater would tend to abrade that side; and (3) if theforging stock continued to lay on one side, that side would be shieldedagainst radiant heat and the stock would be heated unevenly and moreslowly.

Where lengthwise space is not critical, the preheater cylinder may be inline with (instead of side by side of) the barrel. This utilizes a longnarrow space and eliminates the necessity of a transfer box.

In FIGS. 7 and 8, the details of one form of refractory inserts which Ihave developed for use in the tumbler barrel 10 are illustrated.However, such refractory inserts could also be utilized in other furnacestructures and other forms as later disclosed could be used in furnace10. In phantom, in FIG. 7 is shown the outer furnace shell 120 which, asillustrated, is the shell of the tumbler barrel 10. A hollow refractorycore 122 fits snugly within the shell 120 and has an inner cylindricalwall portion 124 defining the inner walls of the furnace and hasoutwardly extending spaced legs 126A, 1268, etc. extending into contactwith the shell 120. These legs 126A, 1268, etc. rigidly support the core122 in the shell 120. The spaces 128A, 1288, etc. between the legs, theinner wall 124, and the shell lare filled with insulation, which Iprefer to be diatomacious earth.

My structure secures the advantages of the rigidity and hardness of arefractory, such as alumina, and the excellent insulating properties ofa soft material like diatomacious earth.

When used in the tumbler barrel 10, a series of identical inserts aremounted end to end along the cylindrical shell of the barrel.Preferably, their legs are aligned so that the insulation can be easilyfilled in after all the inserts have been mounted in the shell.

OPERATION AND THE CONTROL CIRCUIT Each step of the following describedoperation could be manually initiated in a manner which should beobvious. For example, each electrical device, pneumatic device andmechanical device could be manually operated by means of switches,valves and levers. The preferred operation, described generally, beginswith the stacking of stock in the preheat oven 70 and the ignition ofthe burner 50.

After the equipment is brought to operating temperature, a bar of stockis injected or inserted into the barrel 10 by the pneumatic cylinders 80and 82. The vibratory drive is activated and stock is periodicallyinjected into the barrel until the barrel is filled with a series oflongitudinally spaced bars of stock.

At this point the rotary drive begins and the vibratory drive ceases.The bars will then simply roll around the interior of the barrel andbecome evenly heated. At desired intervals. rotation is halted andvibration initiated until a bar falls out the trap door. Then a new baris injected, vibration halted. and rotation begun until an other heatedbar is desired.

FIG. 9 illustrates the control circuit I prefer to use to automaticallyoperate the apparatus described above. The operation of the preferredautomatic embodiment is now described simultaneously with thedescription of the control circuit.

Control circuit power is applied atterminals T1 and T2 and fused by afuse 202. A master-start-stop circuit is provided in which contacts RL2Bclose to apply power to the control circuit. When the master-startcontrol button 204 is depressed, relay RL2 is energized and both thelatching contacts RL2A and contacts RLZB'are closed to energize thecircuit. A pilot light LTl indicates the energization' of RL2. The wholesys-' tem is shut down by depressing the normally closed master-stopbutton 206 thereby de-energizing RL2.

-When contacts RLZB close, and with the automatic operation switch 208closed, power is applied to the timing circuitry. This occurrence isindicated by a pilot light LT2. Timer T2 is immediately energizedthrough normally closed contacts RLlA. The mode of operation of thetimer T2 is such that after a short time delay after it is energized, itcloses the contacts T2A.

Closing the contacts T2A energizes the main timer motor and clutch TMland TC 1 respectively which in turn immediately closes contacts TIA andT18. The closing of contacts TlA latches the timer Tl so that whencontacts T2A open (when contacts RLlA later open) the timer Tl willstill remain energized.

When contacts TlB close, the vibration motor starter M82 and the timerTM3 are energized through the normally closed contacts RLlB. Controlpanel pilot light LT3 is also illuminated. At this point, vibration ofthe barrel begins and the bars of stock begin moving longitudinallyalong the barrel. The timer TM3 is a warning device which, as will beapparent, will close contacts T3 to cause visible and audible signalsLT7 and HR to be actuated if no bar of stock has fallen from the trapdoor 56 within a specified time, such as 7 seconds.

With the vibration motor now operating, the bars of stock will be movingtoward the stationary compartment 49. The vibration motor will continueand the control circuit will remain in the same state until a bar ofstock falls onto the trap door 56 and moves it to its position 56a. Alimit switch LS1 (see FIG. 2) is mounted beside the trap door 56 so thatit is actuated when the trap door moves to the position 56a. Thus, insummary, the vibration motor continues until a bar of stock falls ontothe trap door 56 and thus closes the normally open contacts of the limitswitch, those contacts being LSlA and LSlB.

The closing of contacts LSlA energizes relay RLl thus opening contactsRLlA and RLlB and closing contacts RLlC and RLID. The opening ofcontacts RLlA de-energizes the timer T2 and thereby opens contacts T2A.However, the main timer Tl remains energized through contacts TlA.Simultaneously, the opening of contacts RLlB stops the warning timermotor TM3 and stops the vibration motor M82. The closing of contactsRLlC latches relay RLl to its energized position after contacts LSlAreopen. The closing of contacts RLlD energizes the rotation motor MS]and simultaneously illuminates the control panel pilot light LT4.Therefore, the effect of closing contacts LSlA is to stop the vibrationmotor, initiate operation of the rotation motor, and stop the warningtimer TM3.

As stated above, when a bar of stock falls on the trap door, thecontacts LSlB are also closed. Thus, simultaneously with the aboveactivity, the timer motor T4 is actuated and, if the automatic feedcontrol switch 299 is closed, power is applied to the solenoid SOL-l.Actuation of power to the solenoid SCL-l causes operation of the stockinjection means comprising the cylinders 80 and 82. The solenoid SOL-lactuates the pneumatic circuit which causes the cylinders 80 and 82 tomove a bar of stock to the position 112A and then inject it into thebarrel and to retract to their original positions.

The timer T4 is for holding the bar of stock on the trap door while itstemperature is being read by the temperature reading device 61. Forexample, the timer T4 might delay 2 seconds from the time contacts LSlBare closed until the contacts T4 are closed. The closing of contacts T4actuates the solenoid SOL-2 which in turn trips the pneumatic circuit toactuate the pneumatic cylinder 53 and thereby open the trap door 56 tothe position 56B, permitting the bar of stock to fall or roll onto aplatform. An operator then lifts the bar of stock and positions it inthe forge.

The trap door 56 opens until an arcuate cam (not shown) formed on thetrap door 56 releases the limit switch LS1 so that contacts LSlA andLBlB may open. When contact LSlB opens, power is no longer supplied totimer T4 to hold contacts T4 closed nor is power supplied to solenoidSOL-l and the trap door returns to its closed position without closingthe contacts of limit switch LS1. The opening of contacts LSlA has noeffect because relay RLl is held energized by the latching contactsRLlC. The circuit will now continue in this state, with the rotationmotor operating and the vibration motor not operating, so that the barswill roll around the interior of the barrel and continue to be uniformlyheated, since it will continue in this stateuntil the timer Tl has runfor its set period of time. The length of time set in timerTl determinesthe period of bar stock delivery through the trap door. Thus, if a baris desired every 30 seconds, for example, the timer T1 is set for 30seconds.

After the time set in timer Tl has elapsed, contacts TlA and T18 willagain open. The opening of contacts TlA de-energizes the timer T1 andpermits it to reset. The opening of contacts TlB de-energizes the motorcircuitry for rotation motor M51 and returns it to its initial states.Thus, opening of contacts TlB de-energizes the relay TLl thereforeclosing contacts RLlA and RLlB and opening contacts RLlC and RLlD. Thisinstantly reapplies power to time delay timer T2 to begin the cycleagain. The delay in timer T2 is to permit a sufficient time for thetimer T1 to reset itself.

Where desired, counters CR1 and CR2 may be positioned as shown to countone unit each time contacts TlB are closed. Thus the counters will countthe cycles of operation and therefore the number of bars of stock whichpass through the trap door. Counter CR1 can be reset at will to countthe number of units of a particular job. Counter CR2 counts the totalcycles the apparatus has operated.

g The embodiments shown in FIGS. 10-18 inclusive area are in manyrespects similar to the embodiments shown in FIGS. l-9. However theseembodiments of FIGS. 10 to 18 differ in other respects and thesedifferences constitute important improvements over the structure shownin FIGS. 1-9 inclusive.

The several embodiments disclosed all show the combination of arotatable furnace for the continuous heating of objects with means forrotating the furnace and with separate means for causing longitudinalmovement of objects placed in the furnace along the barrel thereof fromthe inlet end toward the outlet end as well as heating means forsupplying heat into the furnace. All of the embodiments disclose acompartment opening into the outlet end of the barrel, mounted abuttingthe barrel for receiving objects from the barrel and having a trap doorfor permitting objects to drop from the compartment. All of theembodiments disclose electrical controls for at desired times causingthe rotatable barrel to be rotated and at times for causing the barrelto stop and at times when the barrel is stopped from rotating causingthe insertion or injection of objects to be heated into the barrel, theremoval of objects from the barrel and/or the movement of objects alongthe length of the barrel.

All of the embodiments disclose the rolling of the objects around theinterior of the bores through the furnace so that the objects are heateduniformly and so that the objects when moved longitudinally do notalways move while supported by the same side of the object. Thiseliminates undue wear on one side. All of the embodiments disclosed haveelectrical controls for starting and stopping the rotation of the barreland for energizing the means for inserting objects to be heated into thebarrel, for removing heated objects from the barrel and/or moving theobjects being heated from one end of the barrel to the other during thetime that the barrel is stopped from rotating. All of the embodimentsdisclose an arrangement wherein the inner core of the barrel is formedby a plurality of aligned segments of a ceramic material.

However, in the embodiment shown in FIGS. 10-18 no means are providedfor longitudinally vibrating the barrel to achieve longitudinal movementof the objects along the barrel from the inlet end to the outlet end.Moreover in theembodiments shown in FIGS. 10-18 there are shown aplurality of passages extending through the rotating barrel whereby thecapacity of the furnace is greatly increased to the extent ofapproximately the product of the capacity of a single bore furnacemultiplied by the number of bores provided. In order to minimize scalingit is desirable to have the objects heated by a non-oxidizing flame atthe time that they are at the highest temperature and by an oxidizingflame only at the time that they are at a relatively low temperaturewhereby scaling is substantially eliminated. Therefore in theembodiments shown in FIGS. 10-18 an oxidizing stream of heating gas anda separate reducing stream of heating gas is injected into the furnace.Means are provided so that only the reducing stream contacts the objectsbeing heated when the objects are at a relatively high temperature butthe two streams mix to achieve complete combustion.

With the above in mind and referring especially in FIGS. 10-12inclusive, it may be seen that I have shown therein a substantiallyhorizontal rotatably mounted barrel 410 supported on a plurality ofpairs of rollers such as rollers 412a and 412b which are mounted insupport arms 414 which are in turn weldedto an underframe 416 consistingof upper horizontal members such as 418 supported by vertical strutssuch as the vertical strut 420 which are in turn supported by the base422. The barrel 410 is rotatably driven by a motor 432, by a chain 434in a manner similar to the apparatus shown in the embodiment of FIGS.1-9 inclusive. At the outlet end 448 of the barrel 410 is a stationarycompartment 449 to which a pair of gas burner heating means 450 and 451are mounted. Fuel is supplied to the burners 450 and 451 through supplypipes which are not shown. The compartment 449 is mounted on frame 416and is provided with a trap door 456 (See FIGS. 17 and 18) which isperiodically opened to permit objects heated in the barrel 410 to rollout. It may be noted at this point that the trap door unlike the trapdoor of FIGS. 1, 2, and 4 is mounted on a hinge 457 which has its axisextending parallel to the longitudinal axis of the furnace whereby theobjects roll out when-the door is opened rather than fall out. I

The trap door 456' may be provided with a counterweight as is shown inFIG. 17 at 454 and necessarily is provided with a pneumatic controlcylinder 455 as is shown in FIG. 18. It is true, the arrangement of thetrap door 56 shown in FIGS. 1, 2, and 4 may be used if desired. However,I prefer very much to use the arrangement shown in FIG. 18 inasmuch asthereby distortion of the billets as they roll from the compartment 449is minimized or eliminated entirely.

The arrangement of a preheater for loading objects such as billetsintothe furnace barrel 410 as shown at 70 in FIGS. 1, 2, and 5 may beused if desired. However, in view of the improvements in the furnacebarrel 410 such a preheater is ofttimes unnecessary and the arrangementas shown in FIGS. and 12 for loading billets into the furnace barrel 410is in most cases satisfactory.

The utilization of a preheater having a plurality of longitudinalpassages. extending therethrough and arranged parallel to and adjacentto the rotor furnace barrel 410 as described above on pages 13, 14, and15 hereof can be used with the furnace barrel 410 if desired. A transferbox as described in connection with the parallel arranged preheater mayalso be used if desired. However, as stated above the arrangement shownin FIGS. 10 and 12 is normally satisfactory. Therein billets are placedupon or are allowed to roll down into proper position on a shelf 470(FIG. 12) where they can be at the proper time injected into the furnacebarrel 410 by means of a plunger 483 operated by means of a pneumaticcylinder 482.

One very important feature and advantage of the furnace shown in FIGS.10 to 18 inclusive is the arrangement by which the capacity of thefurnace barrel 410 is increased many fold over the capacity of thefurnace 10 (FIG. 1). Referring to FIGS. 11, 13, 14, and 17 especially,it may be seen that the furnace barrel 411) comprises an outer casing orshell 411 which may preferably be of metal. Positioned concentricallywithin the casing 411 is a ceramic core generally designated as 413. Thecore 413 is provided with a plurality of longitudinal passageways suchas passageways 415a, 415b, 415e, 415d, etc. As shown there are eightpassageways clearly shown in FIGS. 11, 13, and 14. When the furnace isoperating these passageways are all filled with objects to be heated.Therefore for an equivalent length the furnace 410 has eight times thecapacity of the furnace 1110f FIG. 1 wherein there is provided only onepassageway. If a greater capacity is desired the number of passageways415 could be increased ifdesired. During all the time that the objectsto be heated are in the passageways they are being heated by gas whichis supplied into the furnace as will later be described more in detail,and consequently a much larger number of objects is being heated at thesame time. The objects to be heated are supplied into the furnace one ata time in one of the passageways. For example. when the furnace barrel410 is in the position shown in FIG. 11 and a billet lies upon the table470 (FIG. 12) and the furnace barrel is stopped from rotating, actuationof the cylinder 482 through the plunger 483 pushes the billet into thepassage 415d. If then the furnace is rotated clockwise as for example,through 180 and is stopped, the cylinder 482 may be actuated to pushanother billet by means of a plunger 483 into the passageway 415a. Ifthe furnace barrel is again rotated through 45 and stopped, then thecylinder 482 and the plunger 483 may be actuated to push another billetinto the passageway 4115b. Similarly if the'furnace barrel is rotatedthrough an additional 45, etc. and stopped the cylinder 482 and theplunger 483 may be actuated to push a billet into the passageway 4150,etc. The electrical system subsequently to be described is so programmedthat billets are alternately pushed into each of the passageways so thatall of the passages of the furnace are filled and each of the billetsremains in'the core of the furnace for an identical length of time. Aseach billet is pushed into one of the passageways as may be understoodespecially from FIG. 17, all of the billets in that same passageway asfor example, in passageway 415d, are moved toward the outlet end and oneis pushed into the outlet box or receptacle 449 (FIGS. 10 and 12). Thebillet 4170 is shown in dotted lines in the receptacle 449. When thecylinder 455 is actuated to open the trap door 456 the billet 417a willroll on the trap door 456 to an outlet position such as is shown fulllines at 417b. The plunger 483 may thus push a billet from the table 470(FIG. 12) into the passageway 415d (FIGS. 11 and 17). This billet willgradually pass through the furnace and eventually will be pushed out asat 417a and when the door 456 is opened will roll on the door as at 417band thus be released from the furnace barrel. As shown most clearly inFIG. 17 the core 413 is spaced concentrically in the furnace barrel 410and is held securely in place by a plurality of screws such as thescrews 426a, 426b, 4260, and 426d as shown in FIG. 17. As indicated inFIG. 13 there are also other identical screws placed circumferentiallyaround the circumference of the core 413. It will be noticed that thecore generally designated as 413, consists as shown in FIGS. 13, 14 and17 of a plurality of separate ceramic sections such as the sections421a, 421b, 4210 and 421d. These are also held in place by the screwssuch as the screws 426a426d inclusive referred to above. The passageways415a, 415b, 4151:, 415d, etc. in each of the segments are aligned witheach other and held in alignment by said screws, and thus eachpassageway forms one continuous passagethrough the whole core. The coreis also provided with a central passageway 407 (FIG. 17) which is muchlarger than the passageways 415a, etc. The axis of the passageway 407 ison the axis of rotation of the furnace barrel. The axes of thepassageways a, etc. are arranged in a circle which is concentric withthe axis of passageway 407. As the furnace barrel rotates, the axis ofeach longitudinal passageway 415, etc. at times is aligned exactly withthe billet which lies upon the table 470.

Another important feature of the furnace disclosed in FIGS. 18 is themeans which I have devised for preventing scale on the objects beingheated, regardless of the fact that the objects are heated at hightemperatures. I accomplish this prevention of scale with most efficientcombustion so as to produce the maximum amount of heat from the fuelused. It will be noticed that as shown in FIGS. 10, 12, and especiallyin FIG. 17 there are two burners 450 and 451. Each of these supplies acombustive mixture of combustible gas and air or oxygen but the mixtureof air or oxygen and gas differs in the two burners. In one case themixture supplied by burner 450 is a reducing mixture and in the othercase, the stream of combustible mixture supplied by the burner 451 is anoxidizing mixture. Pure heated air or pure oxygen could be suppliedinstead of a mixture from 451 but for practical purposes I prefer tosupply an oxidizing combustible mixture of air and. gas from the burner451. This oxidizing mixture supplied from the burner 451 flows into thecentral passageway 407 (see FIG. 17) until it reaches the ceramic block403 positioned adjacent theinlet end of the barrel 410. The pressure ofcombustible gas naturally builds up in the passageway 407 and increasingincrements of the burning oxidizing mixture spread out through openingssuch as 4060, 406b, 406C, and 406d into the passageways 415a, 415b,4150, 415d, etc. The burning oxidizing gas mixes with the burningreducing gas mixture coming from the burner 450.

Thus the billets such as 4170 as they are first introduced into thefurnace at the inlet end are relatively cool and are initially heated bya mixture of the oxidizing stream and the reducingstream. Although themixture of the oxidizing stream and the reducing stream. Although themixture is intended to be stoichiometric at this time, were the billetsrelatively hot, there would be some danger of scaling. However thebillets have not yet been heated to a very high temperature and scalingis avoided. However as the billets proceed through the passages 415a,415b, 415e, and 415d, etc., the heating mixture of combustible gasesbecomes more and more reducing and when the billets approach the outletend of the furnace, there is no danger of scaling because of thereducing gas surrounding the billets entirely as an envelope. That is tosay, that as the billets proceed toward the outlet end of the barrel 410they are gradually heated to their highest temperature and at the outletend of the furnace where they are at their highest temperature the gasmixture coming from the burner 450, is decidedly reducing and there islittle or no tendency to oxidize at this point and form scale. Theamounts of gas mixtures are such that the total mix is stoichiometricand complete combustion is achieved. For example, I may supply a mixtureof gas and air .through the main center burner nozzle which consists ofan excess of air gas, for example, a mixture of gas and air with anexcess of air (or deficiency of gas) of 10 percent. Through the secondburner 450 I supply to all of the passages 415a, 415b, 4150 and 415d,etc., a mixture which has an excess of gas (or a deficiency of air) ofabout percent. In the example given the lean mixture with the 10 percentexcess of air is supplied by the central burner 451 into the centralpassageway 407 and rich mixture with the 50 percent excess of gas issupplied into the several circumferential passageways 415a, etc. Howeverin order to achieve full combustion in this example we would supply arelatively large volume of the lean mix with the 10 percent excess ofair and a relatively small volume of the rich mix with the 50 percentexcess of gas so that when the two are mixed together there will be anexactstoichiometric balance and complete combustion.

Referring now especially to FIG. 16 for a description of the structureof the rotating barrel 410 and the inner core 413 thereof, it may beseen that there is provided a steel casing or shell 411 through whichthe screws 416, etc. extend. The screws bear on metal strips 4040 whichare secured to a stainless steel skin 409 (shown in FIG. 6) which may beof approximately 0.060 thickness and and which surrounds the ceramicsegments 421a, 421b,,421c, 421d, etc. which form the core 413 for thefurnace barrel 410. Each ceramic segment may be formed of two differenttypes of ceramic such as an insulating ceramic 405 and a high aluminaceramic 406 as shown in FIG. 16.

The electric controls are similar to the electric controls shown in FIG.9 but they are modified so that they control the operation of thefurnace to (1) stop the rotation of the burnace barrel at a position atwhich the billet on the platform 470 is aligned with one of theconcentric passageways such as 415a; (2) then the control operates thepneumatic cylinder 482 to insert a bi]- let into the passage 415a. Thispushes the billets in that passageway forward and the billet next to theoutlet end falls into the compartment 449. The electric controls (3)operate the door 456 to release the billet and (.4) start the rotationof the furnace barrel. At the end of the time period for which eachcycle is set (5) the controls stop the burnace barrel and the cyclerepeats.

Means are provided (see FIGS. 13 and 15) for positioning the core 413relative to the steel casing or shell 411. This means consists of achannel member 408 secured to the inner part of the shell 411 and a keyor lug 408a on the core 413 which fits into the channel as shown inFIGS. 13 and 15.

Means are provided for minimizing the amount of gas, air and/orcombustive mixtures which might otherwise escape through the slightspace between the rotative barrel 410 and the unit which houses theburners 450 and 451 and the compartment 449. This means consists of aplurality of pipes 419 which supply fluid such as steam to exert a backpressure on the gas and combustive mixture and a shield 419a. The shielddoes not extend all of the way around the unit but the small gap at theposition of the trap door 456 does not permit the escape of very much ofsuch gas, air and/or com-.

bustive mixture inasmuch as the shield covers about percent of thecircumference of the barrel.

While the furnace has been described for example, as a furnace forheating forging billets so that they may be forged, it is clear that theinvention as described and as claimed may be used for annealing orotherwise heat treating any suitably shaped objects.

It is to be understood that while the specific examples given describepreferred embodiments of my invention, they are for the purposes ofillustration only, that the method of the invention is not limited tothe precise details and conditions disclosed, and that various changesmay be made therein without departing from the spirit of the inventionwhich is defined by the following claims.

I claim:

1. A furnace for the continuous heating of objects comprising a. asubstantially horizontal, rotatably mounted tumbler heater barrel havingan object inlet end and an object outlet end;

b. means for at times rotationally driving the barrel for rolling theobjects around the interior of the barrel without causing substantiallongitudinal movement of the objects;

c. means forat times causing longitudinal movement of the objects alongthe barrel from the inlet end toward the outlet end; 7

d. a stationary compartment opening into the outlet end of the barrel,mounted abutting the barrel for receiving objects from the barrel, thecompartment having means comprising a trap door for delivering heatedobjects from the compartment; and

e. heating means for supplying heated gases to said stationarycompartment and from said compartment into the outlet end of the barrel.

2.- A furnace for the continuous heating of objects comprising (a) asubstantially horizontal, rotatably mounted tumbler barrel having anobject inlet end and an object outlet end; (b) means for at timesrotationally driving the barrel for rolling the objects around theinterior of the barrel without causing substantial longitudinal movementof the objects; conveyor type vibrating means for longitudinallyvibrating the barrel to provide at times longitudinal movement of theobjects along the barrel from the inlet end toward the outlet end; and(d) heating means at the outlet end for supplying heat into the outletend;

wherein a stationary compartment opening into the outlet end of thebarrel is mounted abutting the barrel for receiving objects from thebarrel, the compartment having a trap door for permitting objects todrop from the compartment.

3. A furnace according to claim 2,

wherein the heating means is a gas burner mounted to the compartment.

4. A furnace according to claim 3,

wherein said burner has two portions with means for directing anoxidizing flame toward the inner surface of said barrel and means fordirecting a reducing flame along the barrel.

5. A furnace for the continuous heating of objects comprising (a) asubstantially horizontal, rotatably mounted tumbler barrel having anobject inlet end and an object outlet end; (b) means for at timesrotationally driving the barrel for rolling the objects around theinterior of the barrel without causing substantial longitudinal movementof the objects; (c) conveyor type vibrating means for longitudinallyvibrating the barrel to provide at times longitudinal movement of theobjects along the barrel from the inlet end toward the outlet end; and(d) heating means at the outlet end for supplying heat into the outletend;

wherein a stationary, pre-heat oven opening into the inlet end of thebarrel is mounted to abut the inlet end of the barrel and is inclined torise therefrom, therein said objects may be stacked and preheated by hotgases flowingfrom the outlet end to the inlet endand thence through thepreheat oven.

6. A furnace according to claim 5, wherein the preheat oven comprises:

a. an inclined platform extending approximately radially upwardly andoutwardly from the axis of the barrel; and

b. cover means including a top and sides to form an enclosed passagewayabove the inclined platform;

wherein said objects may be stacked on the platform and heated.

7. A furnace according to claim 6,

wherein injection means are mounted to the lower end of the oven nearthe abutting barrel for selec tively injecting bar stock objects fromthe platform into the tumbler barrel.

8. A furnace according to claim 7,

wherein the injection means includes an injector plunger mountedparallel to the longitudinal axis of the barrel opposite the inlet endof the barrel for movement toward the inlet end to inject a bar offorging stock from the preheat oven into the barrel.

9. A furnace according to claim 7, wherein the injection means includes:

a. a stop protruding upwardly from the platform for preventing downwardmovement of bars of stock stacked in the oven; and

b. an upwardly moving plunger mounted near the stop for pushing one barof stock over the stop and into position for injection into the barrel.

10. A furnace for the continuous heating of objects comprising (a) asubstantially horizontal, rotatably mounted tumbler barrel having anobject inlet end and an object outlet end; (b) means for at timesrotationally driving the barrel for rolling the objects around theinterior of the barrel without causing substantial longitudinal movementof the objects; (c) conveyor type vibrating means for longitudinallyvibrating the barrel to provide at times longitudinal movement of theobjects along the barrel from the inlet end toward the outlet end; and(d) heating means at the outlet end for supplying heat into the outletend;

wherein a preheat oven having an inlet end and an outlet end is providedand has its outlet end connected to the inlet end of the barrel; objectsintroduced into the inlet end of the preheat oven move from the inletend of said preheat oven to the outlet end thereof; means-are providedfor moving the objects from. the outlet end of said preheat oven intothe inlet end of the barrel; and means are provided for conductingheated gases emerging from the inlet end of said barrel into and throughthe preheat oven whereby said objects are preheated by said heated gaseswhich have flowed from the outlet end of said barrel to the inlet endthereof and then from the outlet end of said preheat oven to the inletend thereof.

11. A furnace according to claim 10,

wherein the preheat oven is a longitudinal oven provided with aplurality of longitudinal passages into which objects being preheatedmay be placed, and is substantially coextensive with and is positionedparallel to the barrel.

12. A furnace according to claim 11,

wherein the preheat oven is cylindrical.

13. A furnace according to claim 10,

wherein means are provided for rotating said preheat oven.

14. A furnace according to claim 10,

wherein the preheat oven is stationary, is mounted to abut the inlet endof the barrel, and is inclined to rise therefrom, and wherein saidobjects may be stacked and preheated by hot gases flowing from theoutlet end of the barrel to the inlet end thereof and thence through thepreheat oven.

15. A method for uniformly heating bars of forging stock to forgingtemperature, the method comprising:

a. rolling the bars along the inner circumference of a tumbler barrel byeffecting rotation of the barrel;

b. simultaneously passing suitably heated gases longitudinally along thebarrel; and

c. periodically vibrating the barrel to convey the bars longitudinallyalong the barrel.

16. A method according to claim 15,

wherein the inner diameter of the barrel is substantially larger thanthe diameter of the forging bars.

17. A method according to claim 16,

wherein the barrel is rotated at approximately 1 revolution per minute.

18. A furnace according to claim 1 wherein the heating means is a gasburner mounted on and secured to the compartment.

19. A furnace according to claim 18,

wherein said burner has two portions with means for directing anoxidizing flame toward the inner surface of said barrel and means fordirecting a reducing flame along the barrel.

20. A furnace for the continuous heating of objects comprising:

a. a substantially horizontal, rotatably mounted barrel having an objectinlet end and an object outlet end and having a plurality of separatepassageways extending from the inlet end to the outlet end;

b. means for at times rotationally driving the barrel for rolling theobjects in order to equalize the heating of the objects on all sideswithout causing substantial longitudinal movement of the objects;

c. means for inserting objects to be heated in one of said passagewaysand causing longitudinal movement of the objects along the passagewayfrom the inlet end toward and out of the outlet end of the barrel;

d. means for inserting other objects to be heated into another of saidpassageways and causing longitudinal movement of the objects in saidsecond, passageway toward and out of the outlet end of the barrel;

e. means adjacent the outlet end of the barrel for receivingobjects fromthe barrel; and

f. heating means for supplying heat into all of the passageways of thebarrel.

21. A furnace according to claim 20,

wherein said heating means comprises: two burners one of which producedheated oxidizing products of combustion and the other of which producesheated reducing products of combustion; and

wherein means are provided for directing a stream of products havingoxidizing characteristics from one of said burners approximatelylongitudinally along a path longitudinally of said barrel and fordirecting a stream of products having reducing characteristics from theother of said burners approximately longitudinally along a pathlongitudinally of said barrel spaced from and approximately parallelwith the first mentioned path.

22. A furnace according to claim 20,

wherein there are produced two streams of heating gas, one of which isan oxidizing stream and the other of which is a reducing stream. andwherein the oxidizing stream is directed along a path extendingapproximately longitudinally of said barrel and not contacting theforging stock which is at a relatively high temperature and the reducingstream is directed along a separate path also extending approximatelylongitudinally of the barrel but spaced from and extending approximatelyparallel with the first mentioned path in such a way as to have thisstream of reducing gas surround the stock which is at the relativelyhigh temperature,

' 23. A furnace according to claim 22, V

wherein the objects being heated which are at a relatively lowertemperature are surrounded by a stream of heating gas which isapproximately stoichrometric and therefore neither oxidizing norreducing.

24. A furnace according to claim 22,

wherein there is only one burner but there are two streams of heatinggas one of which is reducing and one of which is oxidizing.

25. A furnace according to claim 20, comprising:

1. an outer shell;

2. a hollow refractory core consisting of a liner for the outer shell;and

3. means for spacing the core from said shell and for rigidly supportingthe core in said shell.

26. A furnace according to claim 25,

wherein the shell is cylindrical and rotatable and the core comprises aseries of identically shaped inserts mounted in end to end relationshiplongitudinally along the cylindrical shell.

27. A furnace according to claim 25,

wherein the hollow core inner and outer walls are cylindrical and themeans for spacing the core comprises spaced legs formed on the core asradially outwardly extending ridges.

28.A furnace according to claim 25,

wherein the means for spacing and supporting the core comprises: astainless steel casing surrounding the refractory core; a plurality ofslats secured to the casing; and a plurality of threaded studs screwedthrough the shell and bearing on the outer surface of the slats.

29. A furnace according to claim 25,

wherein the core is substantially alumina.

30. A furnace according to claim 20,

wherein a preheat oven is mounted to abut the inlet end of the barrel.

31. A furnace according to claim 30,

wherein injection means are mounted at the lower end of the oven nearthe abutting barrel for selectively injecting objects to be heated intothe barrel.

32. A furnace according to claim 31, wherein the injection meansincludes an injector plunger mounted parallel to the longitudinal axisof the barrel opposite the inlet end of the barrel for movement towardthe inlet end of the barrel to inject bars of forging stock into thebarrel.

33. A furnace according to claim 31,

wherein a platform is provided for storing bars of stock and theinjection means includes:

a. a top protruding upwardly from the platform for at times preventingdownward movement of bars of stock stacked in the oven; and

b. an upwardly moving plunger mounted near the stop for pushing one barof stock over the stop and into position for injection into the barrel.

34. A furnace for the continuous heating of objects comprising: i

a. a substantially horizontal, rotatably mounted, barrel having anobject inlet end and an object outlet end;

b. means for at times rotationally driving the barrel;

and

c. heating means at the outlet end for supplying heat into the outletend;

wherein a preheat oven having an inlet end and an outlet end is providedand has its outlet end connected to the inlet end of the barrel;

objects introduced into the inlet end of the preheat oven move from theinlet end of said preheat oven to the outlet end thereof;

means are provided for moving the objects from the outlet end of saidpreheat oven into the inlet end of the barrel; and

means are provided for conducting heated gases emerging from the inletend of said barrel into and through the preheat oven whereby saidobjects are preheated by said heated gases which have flowed from theoutlet end of said barrel to the inlet end thereof and then from theoutlet end of said preheat oven to the inlet end thereof.

35. A furnace according toclaim 34,

wherein the preheat oven is stationary, is mounted to abut the inlet endof the barrel, and is inclined to rise therefrom; and

wherein said objects may be stacked and after being preheated by hotgases flowing from the outlet end of the barrel, are moved into theobject inlet end of said barrel.

36. A furnace according to claim 20,

wherein the means adjacent the outlet end of the barrel for receivingobjects is provided with a trap door.

37. A furnace according to claim 36,

wherein the trap door has hinges and the axis of continuous heating ofobjects b. means for at times rotationally driving the barrel;

and

c. heating means at the outlet end for supplying heat into the outletend;

wherein the barrel is provided with a core having a plurality ofpassages formed therethrough;

wherein one of the passages is located on the rotative axis of saidbarrel and at least one of said passages is offset from the rotativeaxis.

39. A furnace according to claim 38,

wherein the axial passage has a larger diameter than the offset passage.

40. A furnace for the continuous heating of objects comprising:

a. a substantially horizontally mounted chamber having aninlet end andan outlet end and formed with a plurality of substantially horizontallongitudinal passages through which objects may pass from one end to theother;

b. means for at times causing longitudinal movement of the objects alongthe chamber in at least one of said passages from the inlet end towardthe outlet end;

c. means adjacent the outlet end of the chamber for receiving objectsfrom the chamber; and

d. means for supplying heat into the furnace in at least two streams, atleast one of said streams being a stream of reducing gas supplied intoat least one of said longitudinal passages and the other stream beingafistream of oxidizing gas supplied into at least oneof the other ofsaid longitudinal passages.

41. A furnace according to claim 40,

wherein the chamber is formed with transverse passages spaced from theoutlet end of the chamber for mixing the streams of reducing gas andoxidizing gas.

42. A furnace for the continuous heating of objects comprising:

a. a substantially horizontally mounted chamber having an inlet end andan outlet end and formed with a plurality of substantially horizontallongitudinal passages through which objects may passfrom one end to theother;

b. means for at times causing longitudinal movement of the objects alongthe chamber in at least one of said passages from the inlet end towardthe outlet end;

c. means adjacent the outlet end of the chamber for receiving objectsfrom the chamber; and

d. means for supplying heat into the furnace;

- in which one of the passages is a central passageway and in which allpassageways except the central passageway have their longitudinal axesin a circle which is concentric with the longitudinal axis of thecentral passageway.

43. The structure of claim 22,

wherein the oxidizing flame comprises a lean mixture of air and gaswhere there is approximately 10 percent excess of air over a balancedmixture of air and gas which would achieve neutral oxidationreductionand the reducing flame comprises a rich mixture of air and gas wherethere is approximately a 50 percent excess of gas over said balancedmixture of air and gas.

44. The structure of claim 43, where the rich mixture has an excess ofgas of 55 percent.

45. The structure of claim 43,

wherein the volume of the lean mixture is approximately five times thevolume of gas having the rich mixture.

46. A furnace according to claim 20, wherein a. a preheat oven ismounted to abut the inlet end of the barrel; and b. an inclined platformassociated with said oven and extending radially upwardly and outwardlyfrom the axis of the barrel;

whereby said objects may be stacked on the platform and preheated in thepreheat oven by hot gases flowing from the barrel.

47. A furnace according to claim 22,

wherein there is means for directing the oxidizing 0 flamelongitudinally approximately along the rotational axis of said barreland means for directing the reducing flame longitudinally approximatelyalong an outer portion of the barrel.

48. A furnace for the continuous'heating of objects comprising:

l. a substantially horizontally mounted chamber having an inlet end andan outlet end and formed with a plurality of substantially horizontallongitudinal passages through which objects may pass from'one end to theother;

2. means for at times causing longitudinal movement of, the objectsalong the chamber in at least one of said passages from the inlet endtoward the outlet 3. means adjacent the outlet end of the chamber forreceiving objects from the chamber; and

4. means for supplying heat into the furnace; wherein a. the chambercomprises a rotatable mounted barrel, said barrel being formed with acentral passageway extending longitudinally substantially along therotational axis of said barrel and with a plurality of longitudinalpassageways positioned outwardly of said barrel all at equal distancesfrom said central passageway;

b. means is provided for, at times, rotationally driving the barrel; and

c. heating means is provided at the outlet end for supplying heat intothe central passageway at the outlet end of the barrel and for supplyingheat into at least one of the outwardly positioned passageways.

49. The structure of claim 48 in which one of the heating means suppliesan oxidizing stream of heat and the other heating means supplies areducing stream of heat.

50. The structure of claim 49,

wherein the oxidizing stream is supplied to the central passageway andthe reducing stream is supplied 50 to an outwardly positionedpassageway.

51. The structure of claim 3, in which transverse passageways areprovided connecting the central longitudinal pasageway with theoutwardly positioned longitudinal passageways for the purpose of mixingthe oxidizing gas and the reducing gas to achieve complete combustion.

52. The structure of claim 51,

wherein the transverse passageways are provided downstream from theburner and where the object comprising:

temperature is low enough to avoid oxidation of the objects beingheated.

53. A method of heating objects comprising:

a. heating said objects at a relatively low temperature by a stream ofproducts of combustion of an approximately stoichrometric mixture ofairand gas; and

b. continuing said heating of said objects to a relatively hightemperature by a stream of products of combustion which compose areducing mixture of air and gas.

54. A furnace for the continuous heating of objects comprising:

a. a substantially horizontal chamber having an inlet end and an outletend;

b. means for at times causing movement of objects being heated from theinlet end toward the outlet end of said chamber; and

c. means for producing two streams of heating gas one of which is anoxidizing stream and the other of which is a reducing stream wherein theoxidizing stream is directed along a path in which it does not contactthe objects which are at a relatively high temperature and wherein thereducing stream is directed along a separate path to surround theobjects which are at a relatively high temperature.

5 5. A refractory furnace liner for use in an outer furnace shell, theliner comprising:

a. a hollow refractory core comprising (1) and inner wall portiondefining the 'i'rine'r wall of the furnace, and (2)"outwardly extendingspaced legs extending into contact with said shell for rigidlysupporting the core in the shell; and g b. insulation in the spacesbetween the legs and between said inner walls and said shell.

56. A furnace liner according to claim 55 wherein the shell iscylindrical and rotatable and the liner comprises a series of identicalinserts mounted in end to end relationship longitudinally along thecylindrical shell.

57. A furnace for the continuous heating of objects a. a substantiallyhorizontal chamber having an inlet end and an outlet end and having aplurality of passageways extending from the inlet end to the outlet end;

b. means for supplying heat to said passageways t heat objects which maybe therein;

c. means for inserting any object to be heated in one of saidpassageways and for pushing objects already being heated insaid'passageway toward and out of the outlet end of said chamber; and

d. .means for inserting an object to be heated into a second of saidpassageways with disturbing objects in said first named passageways andfor pushing objects already being heated in said second passagewaytoward and out of the outlet end of said chamber.

a: a: a

"M050 UNITED STATES PATENT OFFICE- (ZERTIFTCAEEE 9F CURRECTION patent3,816,064 I mama June 11, 1974 Ihventor( SigdOIl A. EliOt It iscertified that error appears in the above-identified patent and thatsaid letters Patent are hereby corrected as shown below:

I" "1 column 3, line 92' so as to shown the" should read so as to showthe column 4,1ine' 13: "would direct a reading flame" should read woulddirect a reducing flame column 9,1ines 54 55: "contacts TlB de-energizesthe relay TLl'" should read contacts T'lBdeenergizes the relay RLlcolumn 13, lines 37--38: "Although the mixture of the oxidizing streamand the reducing stream." should be deleted;

column 13, line 6.0: I "which consists of an excess of air gas, forexample" should read which consists of an excess of air.

as, for example column 14, lines 13-14: "screws 416, etc. extend" shouldread screws 426, etc, extend column 15, line 65: "therein said objects"should read whereinsaid objects Signed and sealed this 19th day ofNovember 1974.

(SEAL) Attest:

MCCOY-M. GIBSON JR. 0; MARSHALL DANN Attesting Officer Commissioner ofPatents

1. A furnace for the continuous heating of objects comprising a. asubstantially horizontal, rotatably mounted tumbler heater barrel havingan object inlet end and an object outlet end; b. means for at timesrotationally driving the barrel for rolling the objects around theinterior of the barrel without causing substantial longitudinal movementof the objects; c. means for at times causing longitudinal movement ofthe objects along the barrel from the inlet end toward the outlet end;d. a stationary compartment opening into the outlet end of the barrel,mounted abutting the barrel for receiving objects from the barrel, thecompartment having means comprising a trap door for delivering heatedobjects from the compartment; and e. heating means for supplying heatedgases to said stationary compartment and from said compartment into theoutlet end of the barrel.
 2. means for at times causing longitudinalmovement of the objects along the chamber in at least one of saidpassages from the inlet end toward the outlet end;
 2. a hollowrefractory core consisting of a liner for the outer shell; and
 2. Afurnace for the continuous heating of objects comprising (a) asubstantially horizontal, rotatably mounted tumbler barrel having anobject inlet end and an object outlet end; (b) means for at timesrotationally driving the barrel for rolling the objects around theinterior of the barrel without causing substantial longitudinal movementof the objects; (c) conveyor type vibrating means for longitudinallyvibrating the barrel to provide at times longitudinal movement of theobjects along the barrel from the inlet end toward the outlet end; and(d) heating means at the outlet end for supplying heat into the outletend; wherein a stationary compartment opening into the outlet end of thebarrel is mounted abutting the barrel for receiving objects from thebarrel, the compartment having a trap door for permitting objects todrop from the compartment.
 3. A furnace accoRding to claim 2, whereinthe heating means is a gas burner mounted to the compartment.
 3. meansfor spacing the core from said shell and for rigidly supporting the corein said shell.
 3. means adjacent the outlet end of the chamber forreceiving objects from the chamber; and
 4. A furnace according to claim3, wherein said burner has two portions with means for directing anoxidizing flame toward the inner surface of said barrel and means fordirecting a reducing flame along the barrel.
 4. means for supplying heatinto the furnace; wherein a. the chamber comprises a rotatable mountedbarrel, said barrel being formed with a central passageway extendinglongitudinally substantially along the rotational axis of said barreland with a plurality of longitudinal passageways positioned outwardly ofsaid barrel all at equal distances from said central passageway; b.means is provided for, at times, rotationally driving the barrel; and c.heating means is provided at the outlet end for supplying heat into thecentral passageway at the outlet end of the barrel and for supplyingheat into at least one of the outwardly positioned passageways.
 5. Afurnace for the continuous heating of objects comprising (a) asubstantially horizontal, rotatably mounted tumbler barrel having anobject inlet end and an object outlet end; (b) means for at timesrotationally driving the barrel for rolling the objects around theinterior of the barrel without causing substantial longitudinal movementof the objects; (c) conveyor type vibrating means for longitudinallyvibrating the barrel to provide at times longitudinal movement of theobjects along the barrel from the inlet end toward the outlet end; and(d) heating means at the outlet end for supplying heat into the outletend; wherein a stationary, pre-heat oven opening into the inlet end ofthe barrel is mounted to abut the inlet end of the barrel and isinclined to rise therefrom, therein said objects may be stacked andpreheated by hot gases flowing from the outlet end to the inlet end andthence through the preheat oven.
 6. A furnace according to claim 5,wherein the preheat oven comprises: a. an inclined platform extendingapproximately radially upwardly and outwardly from the axis of thebarrel; and b. cover means including a top and sides to form an enclosedpassageway above the inclined platform; wherein said objects may bestacked on the platform and heated.
 7. A furnace according to claim 6,wherein injection means are mounted to the lower end of the oven nearthe abutting barrel for selectively injecting bar stock objects from theplatform into the tumbler barrel.
 8. A furnace according to claim 7,wherein the injection means includes an injector plunger mountedparallel to the longitudinal axis of the barrel opposite the inlet endof the barrel for movement toward the inlet end to inject a bar offorging stock from the preheat oven into the barrel.
 9. A furnaceaccording to claim 7, wherein the injection means includes: a. a stopprotruding upwardly from the platform for preventing downward movementof bars of stock stacked in the oven; and b. an upwardly moving plungermounted near the stop for pushing one bar of stock over the stop andinto position for injection into the barrel.
 10. A furnace for thecontinuous heating of objects comprising (a) a substantially horizontal,rotatably mounted tumbler barrel having an object inlet end and anobject outlet end; (b) means for at times rotationally driving thebarrel for rolling the objects around the interior of the barrel withoutcausing substantial longitudinal movement of the objects; (c) conveyortype vibrating means for longitudinally vibrating the barrel to provideat times longitudinal movement of the objects along the barrel from theinlet end toward the outlet end; and (d) heating means at the outlet endfor supplying heat into the outlet end; wherein a preheat oven having aninlet end and an outlet end is provided and has its outlet end connectedto the inlet end of the barrel; objects introduced into the inlet end ofthe preheat oven move from the inlet end of said preheat oven to theoutlet end thereof; means are provided for moving the objects from theoutlet end of said preheat oven into the inlet end of the barrel; andmeans are provided for conducting heated gases emerging from the inletend of said barrel into and through the preheat oven whereby saidobjects are preheated by said heated gases which have flowed from theoutlet end of said barrel to the inlet end thereof and then from theoutlet end of said preheat oven to the inlet end thereof.
 11. A furnaceaccording to claim 10, wherein the preheat oven is a longitudinal ovenprovided with a plurality of longitudinal passages into which objectsbeing preheated may be placed, and is substantially coextensive with andis positioned parallel to the barrel.
 12. A furnace according to claim11, wherein the preheat oven is cylindrical.
 13. A furnace according toclaim 10, wherein means are provided for rotating said preheat oven. 14.A furnace according to claim 10, wherein the preheat oven is stationary,is mounted to abut the inlet end of the barrel, and is inclined to risetherefrom, and wherein said objects may be stacked and preheated by hotgases flowing from the outlet end of the barrel to the inlet end thereofand thence through the preheat oven.
 15. A method for uniformly heatingbars of forging stock to forging temperature, the method comprising: a.rolling the bars along the inner circumference of a tumbler barrel byeffecting rotation of the barrel; b. simultaneously passing suitablyheated gases longitudinally along the barrel; and c. periodicallyvibrating the barrel to convey the bars longitudinally along the barrel.16. A method according to claim 15, wherein the inner diameter of thebarrel is substantially larger than the diameter of the forging bars.17. A method according to claim 16, wherein the barrel is rotated atapproximately 1 revolution per minute.
 18. A furnace according to claim1 wherein the heating means is a gas burner mounted on and secured tothe compartment.
 19. A furnace according to claim 18, wherein saidburner has two portions with means for directing an oxidizing flametoward the inner surface of said barrel and means for directing areducing flame along the barrel.
 20. A furnace for the continuousheating of objects comprising: a. a substantially horizontal, rotatablymounted barrel having an object inlet end and an object outlet end andhaving a plurality of separate passageways extending from the inlet endto the outlet end; b. means for at times rotationally driving the barrelfor rolling the objects in order to equalize the heating of the objectson all sides without causing substantial longitudinal movement of theobjects; c. means for inserting objects to be heated in one of saidpassageways and causing longitudinal movement of the objects along thepassageway from the inlet end toward and out of the outlet end of thebarrel; d. means for inserting other objects to be heated into anotherof said passageways and causing longitudinal movement of the objects insaid second passageway toward and out of the outlet end of the barrel;e. means adjacent the outlet end of the barrel for receiving objectsfrom the barrel; and f. heating means for supplying heat into all of thepassageways of the barrel.
 21. A furnace according to claim 20, whereinsaid heating means comprises: two burners one of which produced heatedoxidizing products of combustion and the other of which produces heatedreducing products of combustion; and wherein means are provided fordirecting a stream of products having oxidizing characteristics from oneof said burners approximately longitudinally along a path longitudinallyof said barrel and for directing a stream of products having reducingcharacteristics from the other of said burners approximatelylongitudinally along a path longitudinally of said barrel spaced fromand approximately parallel with the first mentioned path.
 22. A furnaceaccording to claim 20, wherein there are produced two streams of heatinggas, one of which is an oxidizing stream and the other of which is areducing stream, and wherein the oxidizing stream is directed along apath extending approximately longitudinally of said barrel and notcontacting the forging stock which is at a relatively high temperatureand the reducing stream is directed along a separate path also extendingapproximately longitudinally of the barrel but spaced from and extendingapproximately parallel with the first mentioned path in such a way as tohave this stream of reducing gas surround the stock Which is at therelatively high temperature.
 23. A furnace according to claim 22,wherein the objects being heated which are at a relatively lowertemperature are surrounded by a stream of heating gas which isapproximately stoichrometric and therefore neither oxidizing norreducing.
 24. A furnace according to claim 22, wherein there is only oneburner but there are two streams of heating gas one of which is reducingand one of which is oxidizing.
 25. A furnace according to claim 20,comprising:
 26. A furnace according to claim 25, wherein the shell iscylindrical and rotatable and the core comprises a series of identicallyshaped inserts mounted in end to end relationship longitudinally alongthe cylindrical shell.
 27. A furnace according to claim 25, wherein thehollow core inner and outer walls are cylindrical and the means forspacing the core comprises spaced legs formed on the core as radiallyoutwardly extending ridges.
 28. A furnace according to claim 25, whereinthe means for spacing and supporting the core comprises: a stainlesssteel casing surrounding the refractory core; a plurality of slatssecured to the casing; and a plurality of threaded studs screwed throughthe shell and bearing on the outer surface of the slats.
 29. A furnaceaccording to claim 25, wherein the core is substantially alumina.
 30. Afurnace according to claim 20, wherein a preheat oven is mounted to abutthe inlet end of the barrel.
 31. A furnace according to claim 30,wherein injection means are mounted at the lower end of the oven nearthe abutting barrel for selectively injecting objects to be heated intothe barrel.
 32. A furnace according to claim 31, wherein the injectionmeans includes an injector plunger mounted parallel to the longitudinalaxis of the barrel opposite the inlet end of the barrel for movementtoward the inlet end of the barrel to inject bars of forging stock intothe barrel.
 33. A furnace according to claim 31, wherein a platform isprovided for storing bars of stock and the injection means includes: a.a top protruding upwardly from the platform for at times preventingdownward movement of bars of stock stacked in the oven; and b. anupwardly moving plunger mounted near the stop for pushing one bar ofstock over the stop and into position for injection into the barrel. 34.A furnace for the continuous heating of objects comprising: a. asubstantially horizontal, rotatably mounted, barrel having an objectinlet end and an object outlet end; b. means for at times rotationallydriving the barrel; and c. heating means at the outlet end for supplyingheat into the outlet end; wherein a preheat oven having an inlet end andan outlet end is provided and has its outlet end connected to the inletend of the barrel; objects introduced into the inlet end of the preheatoven move from the inlet end of said preheat oven to the outlet endthereof; means are provided for moving the objects from the outlet endof said preheat oven into the inlet end of the barrel; and means areprovided for conducting heated gases emerging from the inlet end of saidbarrel into and through the preheat oven whereby said objects arepreheated by said heated gases which have flowed from the outlet end ofsaid barrel to the inlet end thereof and then from the outlet end ofsaid preheat oven to the inlet end thereof.
 35. A furnace according toclaim 34, wherein the preheat oven is stationary, is mounted to abut theinlet end of the barrel, and is inclined to rise therefrom; and whereinsaid objects may be stacked and after being preheated by hot gasesflowing from the outlet end of the barrel, are moved into the objectinLet end of said barrel.
 36. A furnace according to claim 20, whereinthe means adjacent the outlet end of the barrel for receiving objects isprovided with a trap door.
 37. A furnace according to claim 36, whereinthe trap door has hinges and the axis of hinges of the trap door issubstantially horizontal and substantially parallel to the rotative axisof the rotatable barrel.
 38. A furnace for the continuous heating ofobjects comprising: a. a substantially horizontal rotatably mountedbarrel having an object inlet end and an object outlet end; b. means forat times rotationally driving the barrel; and c. heating means at theoutlet end for supplying heat into the outlet end; wherein the barrel isprovided with a core having a plurality of passages formed therethrough;wherein one of the passages is located on the rotative axis of saidbarrel and at least one of said passages is offset from the rotativeaxis.
 39. A furnace according to claim 38, wherein the axial passage hasa larger diameter than the offset passage.
 40. A furnace for thecontinuous heating of objects comprising: a. a substantiallyhorizontally mounted chamber having an inlet end and an outlet end andformed with a plurality of substantially horizontal longitudinalpassages through which objects may pass from one end to the other; b.means for at times causing longitudinal movement of the objects alongthe chamber in at least one of said passages from the inlet end towardthe outlet end; c. means adjacent the outlet end of the chamber forreceiving objects from the chamber; and d. means for supplying heat intothe furnace in at least two streams, at least one of said streams beinga stream of reducing gas supplied into at least one of said longitudinalpassages and the other stream being a stream of oxidizing gas suppliedinto at least one of the other of said longitudinal passages.
 41. Afurnace according to claim 40, wherein the chamber is formed withtransverse passages spaced from the outlet end of the chamber for mixingthe streams of reducing gas and oxidizing gas.
 42. A furnace for thecontinuous heating of objects comprising: a. a substantiallyhorizontally mounted chamber having an inlet end and an outlet end andformed with a plurality of substantially horizontal longitudinalpassages through which objects may pass from one end to the other; b.means for at times causing longitudinal movement of the objects alongthe chamber in at least one of said passages from the inlet end towardthe outlet end; c. means adjacent the outlet end of the chamber forreceiving objects from the chamber; and d. means for supplying heat intothe furnace; in which one of the passages is a central passageway and inwhich all passageways except the central passageway have theirlongitudinal axes in a circle which is concentric with the longitudinalaxis of the central passageway.
 43. The structure of claim 22, whereinthe oxidizing flame comprises a lean mixture of air and gas where thereis approximately 10 percent excess of air over a balanced mixture of airand gas which would achieve neutral oxidation-reduction and the reducingflame comprises a rich mixture of air and gas where there isapproximately a 50 percent excess of gas over said balanced mixture ofair and gas.
 44. The structure of claim 43, where the rich mixture hasan excess of gas of 55 percent.
 45. The structure of claim 43, whereinthe volume of the lean mixture is approximately five times the volume ofgas having the rich mixture.
 46. A furnace according to claim 20,wherein a. a preheat oven is mounted to abut the inlet end of thebarrel; and b. an inclined platform associated with said oven andextending radially upwardly and outwardly from the axis of the barrel;whereby said objects may be stacked on the platform and preheated in thepreheat oven by hot gases flowing from the bArrel.
 47. A furnaceaccording to claim 22, wherein there is means for directing theoxidizing flame longitudinally approximately along the rotational axisof said barrel and means for directing the reducing flame longitudinallyapproximately along an outer portion of the barrel.
 48. A furnace forthe continuous heating of objects comprising:
 49. The structure of claim48 in which one of the heating means supplies an oxidizing stream ofheat and the other heating means supplies a reducing stream of heat. 50.The structure of claim 49, wherein the oxidizing stream is supplied tothe central passageway and the reducing stream is supplied to anoutwardly positioned passageway.
 51. The structure of claim 3, in whichtransverse passageways are provided connecting the central longitudinalpasageway with the outwardly positioned longitudinal passageways for thepurpose of mixing the oxidizing gas and the reducing gas to achievecomplete combustion.
 52. The structure of claim 51, wherein thetransverse passageways are provided downstream from the burner and wherethe object temperature is low enough to avoid oxidation of the objectsbeing heated.
 53. A method of heating objects comprising: a. heatingsaid objects at a relatively low temperature by a stream of products ofcombustion of an approximately stoichrometric mixture of air and gas;and b. continuing said heating of said objects to a relatively hightemperature by a stream of products of combustion which compose areducing mixture of air and gas.
 54. A furnace for the continuousheating of objects comprising: a. a substantially horizontal chamberhaving an inlet end and an outlet end; b. means for at times causingmovement of objects being heated from the inlet end toward the outletend of said chamber; and c. means for producing two streams of heatinggas one of which is an oxidizing stream and the other of which is areducing stream wherein the oxidizing stream is directed along a path inwhich it does not contact the objects which are at a relatively hightemperature and wherein the reducing stream is directed along a separatepath to surround the objects which are at a relatively high temperature.55. A refractory furnace liner for use in an outer furnace shell, theliner comprising: a. a hollow refractory core comprising (1) an innerwall portion defining the inner wall of the furnace, and (2) outwardlyextending spaced legs extending into contact with said shell for rigidlysupporting the core in the shell; and b. insulation in the spacesbetween the legs and between said inner walls and said shell.
 56. Afurnace liner according to claim 55, wherein the shell is cylindricaland rotatable and the liner comprises a series of identical insertsmounted in end to end relatIonship longitudinally along the cylindricalshell.
 57. A furnace for the continuous heating of objects comprising:a. a substantially horizontal chamber having an inlet end and an outletend and having a plurality of passageways extending from the inlet endto the outlet end; b. means for supplying heat to said passageways toheat objects which may be therein; c. means for inserting any object tobe heated in one of said passageways and for pushing objects alreadybeing heated in said passageway toward and out of the outlet end of saidchamber; and d. means for inserting an object to be heated into a secondof said passageways without disturbing objects in said first namedpassageways and for pushing objecs already being heated in said secondpassageway toward and out of the outlet end of said chamber.